I went through the steering boot as well. When I pull out my dash for the swap I'm considering putting some grommets in the firewall and closing up the boot holes just for safety reasons.

Fished em through the hole where the ECU wires go through the firewall.

I took out my HVAC, so I put a gromet in one of the old heater core holes and use that. Before that I ran through the steering boot.

I put mine where the throttle cable comes through. I used a dremel to extend the hole a bit that way I could run wires and the boost gauge line through

Bought a gromet and made my under the Speedo cable..

Steering boot for my boost gauge, which is the only one I have installed right now. Does anyone know of a hole that would be open once the AC components are gone? Still have my heater and don't want to hack anything else up really bad.

The a/c evaporator hardlines leave a big hole, also the evaporator drain leaves a smaller hole below that. You will still have to make a hole in the evaporator housing to pass wires into the cabin tho.

I used the steering column boot for my boost guage hose as well, seemed to work well. If your wire is too short just splice it and add more wire